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Saturday, 28 April 2012

X Is For XNA

New research has brought us closer than ever to synthesizing entirely new forms of life. An international team of researchers has shown that artificial nucleic acids - called "XNAs" - can replicate and evolve, just like DNA and RNA.

XNA stands for Xenoribonucleic acid and it's a synthetic DNA that's stronger than the real thing. Every organism on Earth relies on the same genetic building blocks: the the information carried in DNA. But there is another class of genetic building block called "XNA" -- a synthetic polymer that can carry the same information as DNA, but with a different assemblage of molecules.

Scientists use the xeno prefix to indicate that one of the ingredients typically found in the building blocks that make up RNA and DNA has been replaced by something different from what we find in nature — something "alien," if you will.

You can think of a DNA strand like a classmate's lecture notes. DNA polymerase is the pen that lets you copy these notes directly to a new sheet of paper. But let's say your friend's notes are written in the "language" of XNA. Ideally, your XNA-based genetic system would have a pen that could copy these notes directly to a new sheet of paper. What scientists did was create two distinct classes of writing utensil — one pen that copies your friend's XNA-notes into DNA-notes, and a second pen that converts those DNA notes back into XNA-notes.

Of course, nothing would call the indispensability of DNA- or RNA-based life into question more than the generation of an entirely synthetic, alternative life form, built from the ground up entirely by XNA. Such an organism would require XNA capable of driving its own replication, without the aid of any biological molecules. Scientists think this is still a ways off. "Even in its simplest setup... it would be very challenging to develop an XNA system within a cell." Such a system would require XNA capable of self-replication, and capable of undergoing evolution in a self-sustained manner.

That said, their work represent a major step in the right direction. As the molecular machinery designed to manipulate XNAs grows, so, too, will the capacity for synthetic genetic systems to stand and operate on their own.